I did a second look at a program that was interviewing almost 40 for 1 position. I was very interested in the program and felt that by returning, perhaps I'd stand out from the crowd. At the time, I got a good vibe about it and I felt like it was going to make a difference. In the end, I'm not sure it changed the outcome anymore than just expressing strong interest to the PD would have done via email/phone, etc.